31 - Introducing Network Programmability Protocols Flashcards
Scripting can be used to gather data or modify configurations. While using a language like Python allows an administration to perform manual programming, there are tools that can be used specifically for configuration __ and __.
automation, management
When there is a defined manual workflow to perform a set of tasks, proper tools should be used to automate it. It does not make sense to spend an hour performing a change. This change could take just a few minutes by using a properly engineered tool. This process is where Open Source tools such as __, __, __, and __ can dramatically reduce the number of manual interactions with the network.
Puppet, Chef, Ansible, SaltStack
What are some features of Puppet?
o Created in 2005
o Manages systems in a declarative manner. You define the state the target system should be in without worrying how it happens
o Written in Ruby
o Agent-based – software agent needs to be installed on devices you want to manage
What are some features of Chef?
o Same model as Puppet
o Based in Ruby, uses a declarative mode
o Agent based
o Refers to automation instruction as recipes
What are some features of Ansible?
o Alternative to Puppet and Chef
o Written in Python
o Agentless – can integrate and automate any device using any API
o Integrations can use REST, APIs, NETCONF, SSH or even SNMP
o Playbooks are Ansible sets of tasks used to automate devices
What are some features of SaltStack?
o Open source
o Python based
o Developed by Thomas S Hatch and originally released in 2011
o Designed to be easily moulded to divergent enterprise IT use cases through a highly modular and easily extensible design
o Uses a module design that creates Python modules to handle aspects of the available salt systems
___is a data exchange format and open standard. It is easy for humans to read and write and is easy for machines to parse and generate. It is based on a subset of JavaScript and is a text format that is completely language independent.
JavaScript Object Notation (JSON)
JSON is best known for the __ syntax because JSON objects always begin and end with a __.
curly brace
JSON is extremely popular, not only because it is easy to read, but for Python programmers, it natively maps into Python as a Python __. So if you understand __, you understand JSON, and vice versa.
dictionary, dictionaries
On a nexus switch, you can __ commands to JSON to see what output looks like as a JSON object. The data returned with JSON gives a descriptor for every value that is returned, allow for easy interpretation of the data. Management systems will have a much easier job using any data value that is returned with the JSON data than the normal output that an admin see via CLI.
pipe
Although using JSON __ have not been extremely popular for network APIs, it is important to understand that there are ways to model and define constraints of JSON objects using a JSON-schema document
schemas
What is a data model?
- Describe a constrained set of data in the form of a schema language
- Use well-define parameters to standardise the representation of data from a network device so the output among various platforms in the same
- Not used to actually send information to devices and instead rely on protocols such as NETCONF and RESTCONF.
- Device config can be validated against a data model to check if the changes are a valid for the device before committing the changes
Data models can define attributes and answers such as:
- What is the range of a valid VLAN ID?
- Can a VLAN name have spaces in it?
- Should the value be a string or an integer
One misconception is that data models are used to __ data to/from a device. This is not the case. Instead, protocols such a NETCONF/RESTCONF send JSON and XML encoded documents that simply adhere to a given model.
send
___ is a formal contract language with rich syntax and semantics on which you can build applications. It provides these rich semantics that offer constraints, but also provides re-usable structures that can be used between __ models.
Yet Another Next Generation (YANG)
What are some features of YANG?
- Modelling language
- Initially build for NETCONF
- Now also used by RESTCONF
- Models configurations and operational state data
- Provides syntax and semantics
- Utilises reusable data structures
There are different types of YANG models. Notably, there are __ standard and __ specific models.
industry, vendor/platform
What is an industry standard YANG model?
- Standard definition
- Come from various working groups (IETF, ITO, OpenConfig etc)
- Focus is to create vendor and platform independent models
What is a Cisco common YANG model?
- Cisco definition
* Common across Cisco devices
What is a Cisco Platform Specific YANG model?
- Cisco definition
* Unique to specific Cisco platforms i.e “BGP” extensions on IOS-XE
There is often a perception that __ is a complex topic to learn about, but it is analogous to browsing a website with a web browser.
Representational State Transfer (REST)
If you understand how to work with a web browser, you understand __. The same HTTP request methods and response codes are used.
REST
When using REST APIs, you still have a client that performs __ operations (GET) to a network device running a web server. The network device understands the request that is based on the URL and returns JSON or XML encoded objects so that the client can properly consume them.
HTTP
What are some features of REST?
- Proposed by Roy Fielding in 2000
- Developed using CRUD operations for use with HTTP
- Stateless client-server model (each request is treated independently from any other request)
- Uses simple URIs to identify resources of interest
